Methyl formate is produced as an intermediate in organic synthesis and is an industrially important raw material for high-purity carbon monoxide, formic acid, formaldehyde, acetic acid, N,N-dimethylformamide, or the like.
There are reported a large number of catalysts for synthesizing methyl formate through the dehydrogenation of methanol in a gas phase. Most of the catalysts are formed of copper as the main component. For example, Patent Document 1 discloses a catalyst consisting of copper, zinc, zirconium, and aluminum, and Patent Document 2 discloses a catalyst consisting of copper oxide, zinc oxide, and aluminum oxide.
There are also proposed catalysts each containing a co-catalyst. For example, Patent Document 3 discloses a method of producing a catalyst by adding a phosphate of copper or the like, a chloride of an alkali metal, alkali earth metal, or the like, and an alkali metal or alkali earth metal compound excluding halides to a mixture of copper oxide, zinc oxide, and aluminum oxide. Patent Document 4 discloses a catalyst consisting of a copper-zinc-aluminum oxide, a phosphoric acid compound, and two or more kinds of alkali metal compounds including lithium.
In the catalyst described in Patent Document 1 or 2 among those catalysts, the content of copper must be increased to improve the methyl formate yield and selectivity. Therefore, the mechanical strength of the catalyst after reductive activation is greatly reduced.
According to the method described in Patent Document 3, it is said that a catalyst having high mechanical strength even after reductive activation and having high methyl formate yield and selectivity can be produced by the function of an additive. With the catalyst described in Patent Document 4, an initial activity and the methyl formate selectivity are further improved, and it is assumed that this is mainly due to an effect obtained by adding lithium.
However, further improvement is required for the practical use of those catalysts from the viewpoint of methyl formate selectivity, durability and heat resistance.